AMSTERDAM (AP) - Dutch museums announced Tuesday they have found 139 artworks that may have been looted during the Nazi era, including paintings from masters such as Matisse, Klee and Kandinsky.

The major review of all museum collections in the country found art that had either dubious or definitely suspect origins.

"These objects are either thought or known to have been looted, confiscated or sold under duress," said Siebe Weide, director of the Netherlands Museums Association. He said returning them is "both a moral obligation and one that we have taken upon ourselves."

The review also listed the names of 20 people whom the museums said definitely had 61 pieces of art taken from them. The museums said they were getting in contact with or seeking their heirs, including the heirs of Jewish art dealer Albert Stern, the deceased owner of the Matisse.

The museum purchased the painting from Lieuwe Bangma family in 1941, but Stern was its owner before the war and the Bangma family is known to have given shelter to his granddaughter during the war.

A previous Dutch review that concluded in 2006 focused on art obtained during World War II. This time all Dutch museums reviewed the chain of possession for all their artwork created any time before the end of the war in 1945, with a special focus on detecting pieces that had any gap in their ownership record after the Nazis came to power in Germany in 1933.

The Dutch are not the first to undertake such a review since a major conference in Washington D.C. on looted art in 1998 that found previous attempt to restore looted art to rightful heirs had been badly flawed. American and British museums have already conducted investigations similar to the Dutch one. In Germany and many other countries, similar investigations are still underway.

"We're not the first with this investigation, but thanks to this investigation we're not far behind," said Rudi Ekkart, a professor at the University of Utrecht who headed the investigating commission.

Among the objects found were 69 paintings, including French painter Henri Matisse's 1921 "Odalisque"painting of a half-nude reclining woman at Amsterdam's Stedelijk museum, one of the country's top tourist draws.

Other paintings included works by old Dutch masters such as Jacob Gerkitsz Cuyp, Impressionist Isaac Israels and modernists Paul Klee and Wassily Kandinsky. Other objects uncovered in the investigation included drawings, sculptures, antiquities and Jewish ceremonial objects.

In a first, the Museums Association was also launching a website Tuesday to publish its findings so far, solicit more information about looted artwork and assist heirs in filing claims. The website will initially only be available in Dutch, but an English translation is expected by the end of 2013, Weide said.

Ekkart said it is still possible that more looted artwork will be uncovered in the Netherlands. He said the museums' investigations were not exhaustive and there are likely pieces held in individual's homes that will be eventually detected.